1. Field of the Invention
The present invention relates to a three-dimensional fabric that is attached to a solid member.
2. Description of the Related Art
Composites having a three-dimensional fabric frame member that is impregnated with a resin or an inorganic matrix material are expected to be widely used as structural members in a variety of applications including rockets, aircraft, automobiles, vessels and buildings. There are two types of three-dimensional fabrics. The first takes the form of a quadratic prism or a plate. The second, which is described in the parent application Ser. No. 07/482,345 has an annular shape.
Traditionally, composites having three-dimensional fabrics as their frame members have not been suitable for coupling to other such composites. The related application Ser. No. 478,352, discloses an arrangement incorporating a solid linkage member into various non-annular three dimensional fabrics.
In contrast, prior art approaches to providing linkage members generally required cutting a whole in the fabric itself. For example, in one know method, a composite having a composite core member formed from a multiplicity of laminated cloth pieces has a hole bored therethrough. A metallic bushing is then inserted in the hole, which allows the composite to be coupled to another composite or another structural member by means of a bolt and a nut.
An application of the same approach to three dimensional fabric based materials requires that a hole be punched into the fabric in order to receive the metallic bushing. However, when a hole is cut in a composite member having a three dimensional fabric as its base, the fabric's strings are necessarily cut which significantly reduces the fabric's overall strength. To regain the strength of that portion, it would be necessary to increase the volume of the portion surrounding the metal bushing. Furthermore, if the hole is punched after a composite member has been formed, subtle cracks may be induced in the composite by the punching action. Such cracks create stress concentrations which weaken the composite member and make it extremely difficult to calculate a given member's actual strength.